The open source mobile OS looks and feels a lot like Android, but is less capable and begs the question of who will want it

For two years, we've been hearing about Tizen smartphones. But we haven't seen any.

Tizen was first promised by Nokia as a replacement for its Symbian OS -- one of several such successors that never saw the light of day, including Maemo and MeeGo. When Nokia switched to Windows Phone, Intel and then Samsung picked up Linux Foundation's Tizen open source project as a lower-end operating system for phones and other devices. Now it's pitched as the "everywhere" OS for the Internet of things.

Tizen has been all hat and no cattle. But now the cows are coming: The poorly reviewed Samsung Gear 2 smart watch is the first device to run the full Tizen OS, and full-Tizen cameras and TVs are promised by Samsung for later this year. And the first Tizen smartphone, the Samsung Z, is due this fall for sale in Russia and other former Soviet-bloc countries. I got a brief chance to try out the Samsung Z this week at the Tizen Developers Conference, and I can tell you that, despite its still-languid pace of development, Tizen is an actual operating system, not just the never-ending research project it has felt like.

The Samsung Z looks and feels very much like Samsung's Android smartphones. There's the tiles section at the top of the home screen, with some app icons at the botton, and there's the pull-down notifications and settings tray at the very top. You also get the hardware Back and Menu buttons, in addition to the main Home button. The Settings app looks almost identical to Samsung's Android version.

None of that is a surprise -- Samsung has said it wants its Tizen phones to feel like its Android phones so that users don't hesitate to stay within the Samsung universe. Back when it had the Bada OS, it espoused the same goal of a largely converged UI.

But there are some differences, and not just in the icon designs. If you swipe up from the app section on the home screen, you get a full-screen window of app icons, similar to the standard iOS home screen. And you don't get the multitasking controls in Android, such as when you swipe in from the side. The Tizen UI may echo the look of Samsung's Android UI, but it's a much simpler interface with only basic gestures to learn. In that regard, it's less complex to master than Canonical's Ubuntu Touch or Mozilla's Firefox OS, both aimed at the same users.